Introduction

Allergic rhinitis is an allergic reaction that occurs when your immune system overreacts to substances that you have inhaled (often pollen). The two types of allergic rhinitis are seasonal allergic rhinitis (hay fever) and perennial allergic rhinitis, which occurs year-round. Hay fever is caused by outdoor allergens, and perennial allergic rhinitis by indoor allergens (such as dust mites, pet dander, mold).

Symptoms of allergic rhinitis resemble a cold, but they are not caused by a virus. When you inhale an allergen, your immune system springs into action, releasing substances known as IgEs into your nasal passages, along with inflammatory chemicals such as histamines. Your nose, sinuses, or eyes may become itchy and congested. Scientists aren't sure what causes your immune system to overreact to an allergen.

Allergic rhinitis is a common condition, affecting about 1 in 5 Americans. Symptoms can be mild or severe. Many people who have allergic rhinitis also have asthma.

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